Quartz crystal vibrator, oscillator and electronic apparatus

ABSTRACT

To provide a quartz crystal vibrator, an oscillator and an electronic apparatus capable of preventing a bonding electrode from being corroded and easily maintaining soundness of the bonding electrode over a long period of time, a quartz crystal vibrator is provided with a quartz crystal vibrating plate formed by surrounding a quartz crystal vibrating piece by a frame-like portion, a hermetically closed vessel including a lid member and a base member in a plate-like shape for interposing the quartz crystal vibrating plate in a thickness direction, bonding electrodes provided between the lid member and the quartz crystal vibrating plate and between the base member and the quartz crystal vibrating plate and electrically connected to an inner electrode, and a protecting film for protecting the bonding electrode, provided with a recess portion recessed to an inner side of the hermetically closed vessel from an outer edge portion between the lid member and the quartz crystal vibrating plate and an outer edge portion between the base member and the quartz crystal vibrating plate, the protecting film is provided at the recess portion and the bonding electrode is disposed on the inner side of the recess portion.

This application claims priority under 35 U.S.C. §119 to Japanese PatentApplication No. JP2005-245684 filed Aug. 26, 2005, the entire content ofwhich is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a quartz crystal vibrator, anoscillator and an electronic apparatus.

2. Description of the Related Art

In recent years, various quartz crystal vibrators are utilized in aportable telephone or a portable information terminal apparatus as atime source, a timing source of a control signal and the like. In thequartz crystal vibrators, there is a quartz crystal vibrating plateformed by surrounding a quartz crystal vibrating piece by a frame-likeportion, and a hermetically closed vessel constituted by interposing thequartz crystal vibrating plate by a lid member and a base member in aplate-like shape in a thickness direction. The quartz crystal vibratorsare fabricated, for example, as follows. That is, a bonding electrodecomprising aluminum or the like is formed on an outer face of a waferfor constituting a quartz crystal vibrating plate, and the quartzcrystal vibrating plate is interposed by two of wafers for constitutingthe lid member and the base member. Thereafter, the respective wafersare anodically bonded by applying a predetermined voltage to each of thewafers, successively, cut to constitute the quartz crystal vibrators oneby one by a dicing step.

Here, when the bonded wafers are cut, end portions of the bondingelectrodes are exposed from side faces of the hermetically closedvessels. The bonding electrode comprises a member having a low corrosionresistance of aluminum or the like and therefore, when the end portionis made to stay to be exposed to outside air, the bonding electrode iscorroded. When corrosion is brought about, leakage is brought about, theatmosphere starts to flow into a cavity portion formed inside of thehermetically closed vessel by a small amount and a pressure of thecavity portion is changed. As a result, an oscillation frequency and aresonance resistance value of the quartz crystal vibrator are varied byrectified values or more. Hence, in order to prevent the variations, itis well known to form a fluororesin layer for covering to protect theend portion of the bonding electrode at the side face of thehermetically closed vessel (refer to JP-A-2003-264447).

However, according to the above-described constitution, a strength ofthe fluororesin layer against an external force is insufficient andtherefore, there is a concern of bringing about chipping or the like atthe fluororesin layer by some factor. Further, although it isconceivable to form the fluororesin layer to be thick in order toincrease the strength, when the fluororesin layer is made to be thick,crack or the like is brought about at the fluororesin layer by a stressproduced by expansion, contraction or the like by a change in atemperature of outside air. When such a chipping or crack or the like isbrought about, outside air or moisture invades from a clearance of thechipping or the crack and the bonding electrode is corroded.

SUMMERY OF THE INVENTION

The invention has been carried out in view of such a situation and it isan object thereof to provide a quartz crystal vibrator, an oscillatorand an electronic apparatus capable of preventing a bonding electrodefrom being corroded and easily maintaining soundness of the bondingelectrode over a long period of time.

In order to resolve the above-described problem, the invention providesthe following means.

According to the invention, there is provided a quartz crystal vibratorcomprising a quartz crystal vibrating plate formed by surrounding aquartz crystal vibrating piece by a frame-like portion, an innerelectrode provided at the quartz crystal vibrating piece for applying avoltage to the quartz crystal vibrating piece, a hermetically closedvessel including a lid member and a base member in a plate-like shapefor interposing the quartz crystal vibrating plate in a thicknessdirection thereof, bonding electrodes for bonding provided between thelid member and the quartz crystal vibrating plate and between the basemember and the quartz crystal vibrating plate and electrically connectedto the inner electrode, and a protecting film provided at an outer faceof the hermetically closed vessel for protecting the bonding electrode,wherein recess portions recessed to inner sides of the hermeticallyclosed vessel are provided at an outer edge portion between the lidmember and the quartz crystal vibrating plate and between the basemember and the quartz crystal vibrating plate, the protecting film isprovided at the recess portion, and wherein the bonding electrode isdisposed on the inner side of the recess portion.

In the quartz crystal vibrator according to the invention, the bondingelectrode is disposed on the inner side of the protecting film andtherefore, the bonding electrode is protected without being exposed tooutside air. Further, since the protecting film is provided at therecess portion recessed to the inner side, a strength of the protectingfilm to the inner side is increased, not only chipping or the like canbe prevented from being brought about but also even when crack or thelike is brought about at the protecting film, the crack can be preventedfrom reaching an end portion on the inner side.

Further, according to the invention, there is provided the quartzcrystal vibrator further comprising an auxiliary electrode electricallyconnected to the bonding electrode and having a corrosion resistancehigher than a corrosion resistance of the bonding electrode, wherein theauxiliary electrode is extended to the outer edge portion between thelid member and the quartz crystal vibrating plate and the outer edgeportion between the base member and the quartz crystal vibrating plate.

In the quartz crystal vibrator according to the invention, the auxiliaryelectrode having the corrosion resistance higher than the corrosionresistance of the bonding electrode is electrically connected to thebonding electrode and is extended to the outer edge portion.

Here, in fabricating the quartz crystal vibrator, it is general tosummarizingly fabricate a plurality of the quartz crystal vibrators byutilizing a wafer. That is, the plurality of quartz crystal vibratorsare continuously formed in row and column directions by overlapping aplurality of wafers. Further, the plurality of wafers are anodicallybonded. That is, respective upper and lower wafers for constituting thelid member and the base member are applied with, for example, a negativevoltage and the bonding electrode is applied with a positive voltagereverse thereto by an outside voltage applying apparatus or the like. Atthis occasion, the bonding electrode of one quartz crystal vibrator isdisposed on the inner side of the recess portion and therefore, thebonding electrode of one quartz crystal vibrator is not connected to thebonding electrode of other quartz crystal vibrator contiguous in row andcolumn directions and respective bonding electrodes are brought into astate of being insulated in singles of the quartz crystal vibrators.Therefore, although the bonding electrodes of the quartz crystalvibrators disposed at an edge of the wafer can be applied with voltageby respectively being connected to an electrode terminal of the voltageapplying apparatus or the like, the bonding electrodes of the quartzcrystal vibrators disposed on the inner side of the wafer cannot beconnected with the electrode terminal.

According to the invention, since the auxiliary electrode is extended tothe edge portion, the respective auxiliary electrodes are brought into astate of being electrically connected to other auxiliary electrodescontiguous in row and column directions. Further, since the respectiveauxiliary electrodes are electrically connected to the respectivebonding electrodes, by only connecting the external electrode terminalto one point of the auxiliary electrode, the voltage can be applied toall of the bonding electrodes on the wafer by way of the auxiliaryelectrode. Therefore, the plurality of quartz crystal vibrators canefficiently and easily be fabricated. Further, since the corrosionresistance of the auxiliary electrode is higher than that of the bondingelectrode, the auxiliary electrode can be prevented from being corrodedby being brought into contact with outside air.

Further, according to the quartz crystal vibrator according to theinvention, an opening diameter of the recess portion is set to be largerthan a diameter of an inner portion of the recess portion.

In the quartz crystal vibrator according to the invention, the meltedprotecting film in a liquid state is injected to the recess portion byway of an opening portion. At this occasion, since the opening diameteris set to be large, the protecting film can easily be injected into therecess portion.

Further, according to the invention, there is provided an oscillator,wherein the above-described quartz crystal vibrator according to anaspect of the invention is electrically connected to an integratedcircuit as an oscillation piece.

Further, according to the invention, there is provided an electronicapparatus including the above-described quartz crystal vibratoraccording to an aspect of the invention.

In the oscillator and the electronic apparatus according to theinvention, an effect similar to that of the above-described quartzcrystal vibrator according to an aspect of the invention can beachieved.

According to the invention, not only chipping or the like can beprevented from being brought about at the protecting film but also evenwhen crack is brought about at the protecting film, the crack can beprevented from reaching the end portion of the inner side and therefore,the bonding electrode can be prevented from being corroded and soundnessof the bonding electrode can easily be maintained over a long period oftime. Further, since the boding electrode is prevented from beingcorroded, leakage is not brought about, a change in a pressure of thecavity portion formed at the inside of the hermetically closed vessel isrestrained and variations in the oscillation frequency and the resonanceresistance value of the quartz crystal vibrator are maintained withinrectified values for a long period of time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plane view showing a quartz crystal vibrator according to afirst embodiment of the invention;

FIG. 2 is a sectional view taken along a line B-B of FIG. 1;

FIG. 3 is a sectional view taken along a line A-A of FIG. 1;

FIG. 4 is an explanatory view showing a behavior of fabricating thequartz crystal vibrator of FIG. 1;

FIG. 5 is an explanatory view enlarging an essential portion of a quartzwafer of FIG. 4;

FIG. 6 is a sectional view taken along a line A-A showing a modifiedexample of a recess portion of the quartz crystal vibrator of FIG. 1;

FIG. 7 is a view showing an essential portion of a quartz crystalvibrator according to a second embodiment of the invention and is asectional view taken along a line A-A in correspondence with FIG. 1;

FIG. 8 is a plane view showing an oscillator according to a thirdembodiment of the invention;

FIG. 9 is a block diagram showing portable information apparatusaccording to a fourth embodiment of the invention; and

FIG. 10 is a block diagram showing a radio wave timepiece according to afifth embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1

A quartz crystal vibrator according to a first embodiment of theinvention will be explained in reference to the drawings as follows.

In FIG. 1, notation 1 designates a quartz crystal vibrator.

The quartz crystal vibrator 1 includes a quartz crystal vibrating plate2 comprising quartz and formed by a rectangular shape, and ahermetically closed vessel 3 having a lid member 6 and a base member 7in a plate-like shape for interposing the quartz crystal vibrating plate2 in a thickness direction.

The quartz crystal vibrating plate 2 includes a quartz crystal vibratingpiece 9 of a tuning fork type in which two of vibrating arms 9 aextended in parallel with each other are integrally connected onrespective base end sides thereof, and a frame-like portion 10 (shown inFIG. 4) in a shape of a rectangular frame surrounding the quartz crystalvibrating piece 9. The quartz crystal vibrating piece 9 and theframe-like portion 10 are integrally formed by way of a base end portionof the quartz crystal vibrating piece 9. As shown by FIG. 2 and FIG. 3,an outer face of the quartz crystal vibrating piece 9 is formed with aninner electrode 24 for applying a voltage to the quartz crystalvibrating piece 9. The inner electrode 24 comprises an electricallyconductive member of, for example, aluminum or the like. Further, byapplying a voltage to the quartz crystal vibrating piece 9 by way of theinner electrode 24, the quartz crystal vibrating piece 9 is vibrated ata predetermined frequency. Further, although in FIG. 2 and FIG. 3, theinner electrode 24 is shown to be simplified, actually, the innerelectrode 24 is naturally patterned in accordance with variousspecifications or shapes.

Further, in two main faces of the lid member 6, one main face 6 a isformed with a lid side recess portion 11 substantially in a rectangularshape. Similarly, a one main face 7 a of the base member 7 is formedwith a base side recess portion 14 substantially in a rectangular shape.Further, the lid member 6 and the base member 7 are bonded byoverlapping the one main face 6 a the other main face 7 a with thequartz crystal vibrating plate 2 interposed therebetween in a state inwhich the lid side recess portion 11 and the base side recess portion 14are opposed to each other. In this way, by making the lid side recessportion 11 and the base side recess portion 14 opposed to each other, acavity portion 15 is formed inside of the hermetically closed vessel 3,and the quartz crystal vibrating piece 9 is permitted to vibrate by thecavity portion 15. Inside of the hermetically closed vessel 3 is sealedin airtight and the cavity portion 15 is maintained in a vacuum state.

Further, an outer peripheral face of the hermetically closed vessel 3 isformed with a protecting film 16 excluding a bottom face (other mainface of the base member 7). The protecting film 16 comprises 0.1 wt %fluorocarbon of a fluorine species coating agent having trimethylsiloxane at a terminus thereof. As the protecting film 16, for example,OPTOOL DSX (product name: made by Daikin Industries, Ltd.) or the likeis used.

Further, bonding electrodes 19 comprising electrically conductivemembers of, for example, aluminum or the like are provided respectivelybetween the lid member 6 and the quartz crystal vibrating plate 2 andbetween the base member 7 and the quartz crystal vibrating plate 2. Thebonding electrodes 19 are for bonding the lid member 6 and the basemember 7, and the quartz crystal vibrating plate 2 and function aslead-out electrodes for extending the inner electrode 24 to theframe-like portion 10. That is, the bonding electrode 19 is integrallyformed with the inner electrode 24 and is electrically connected to theinner electrode 24. Further, the bonding electrode 19 is electricallyconnected with an external terminal 20 provided at the bottom face ofthe hermetically closed vessel 3. The external terminal 20 isconstituted by forming an Au layer on a Cr layer formed as a matrix.

Further, according to the embodiment, there are provided recess portions21 recessed to inner sides of the hermetically closed vessel 3 fromentire peripheries of an outer edge portion between the lid member 6 andthe quartz crystal vibrating plate 2 and an outer edge portion betweenthe base member 7 and the quartz crystal vibrating plate 2. That is, thebonding electrodes 19 formed at the frame-like portion 10 are formed byexcluding the whole peripheries of outer edge portions of the two mainfaces of the quartz crystal vibrating plate 2 and the two outer edgeportions which are not provided with the bonding electrodes 19 areconstituted as the recessed portions 21. Therefore, the bondingelectrode 19 is disposed on the inner side of the hermetically closedvessel 3 of the recess portion 21. Further, the recess portion 21 isfilled with the above-described protecting film 16.

Further, according to the embodiment, matrix electrodes (auxiliaryelectrodes) 25 are formed between the bonding electrode 19 and the onemain face of the quartz crystal vibrating plate 2 (frame-like portion10) and between the bonding electrode 19 and the other main face of thequartz crystal vibrating plate 2 (frame-like portion 10). The matrixelectrode 25 comprises a member having a corrosion resistance higherthan that of the bonding electrode 19, for example, a conductivematerial of Cr, Ti, Ni, W (tungsten) or the like. The matrix electrodes25 are electrically connected to the respective bonding electrodes 19inside of the hermetically closed vessel 3 and respectively extended tothe outer edge portions.

Further, the lid member 6 and the base member 7 comprise glass of, forexample, soda lime glass or the like and the lid member 6 and the basemember 7 are anodically bonded by way of the matrix electrode 25 and thebonding electrode 19.

Next, a method of fabricating the quartz crystal vibrator 1 according tothe embodiment will be explained.

First, the lid member 6 and the base member 7 are machined to form. Thatis, as shown by FIG. 4, a wafer 30 for the lid portion comprising glassis polished to a predetermined thickness and cleaned. Further, a workalterated layer at the topmost surface is removed by etching or thelike. Further, a plurality of the lid side recess portions 11 are formedin one main face 30 a of the wafer 30 for the lid portion by etching orthe like. Further, although in FIG. 4, only one of the lid side recessportion 11 is clearly shown for simple explanation, actually, theplurality of lid side recess portions 11 are formed continuously in rowand column directions over the entire one main face 30 a of the wafer 30of the lid portion. That is, a plurality of the lid members 6 arealigned to be integrally formed into the wafer 30 for the lid portion,and here, the wafer 30 for the lid portion corresponds to the lid member6. Further, the one main face 30 a of the wafer 30 for the lid portioncorresponds to the one main face 6 a of the lid member 6.

Further, the base member 7 is machined to form. That is, similar to thelid member 6, a plurality of the base side recess portions 14 are formedat one main face 31 a of a wafer 31 for the base comprising glass. Alsoin this case, the wafer 31 for the base corresponds to the base member7, and the one main face 31 a of the wafer 31 for the base correspondsto the one main face 7 a of the base member 7.

Successively, through holes, not illustrated, are provided at each offour corners of a rectangle when each of the base side recess portions14 is formed into a rectangle of a predetermined size.

Further, by subjecting a quartz crystal wafer 32 to etching or the like,pluralities of the tuning fork type quartz crystal vibrating pieces 9and the frame-like portion 10 are integrally machined to form. Alsohere, the quartz crystal wafer 32 corresponds to the quartz crystalvibrating plate 2.

Further, after forming a matrix electrode layer over the entire face ofthe quartz crystal wafer 32 by sputtering, vapor deposition or the like,patterning is carried out by photolithography and etching or the like toremove the matrix electrode layer of an inner side face 35 of theframe-like portion 10, the vibrating arm 9 a and the like. The matrixelectrode layer patterned in this way constitutes the above-describedmatrix electrode 25. The matrix electrodes 25 are formed over entire twofaces of the frame-like portion 10 and extended to the outer edgeportion of the frame-like portion 10. Therefore, as shown by FIG. 5, thematrix electrode 25 is integrally formed with the plurality of thequartz crystal vibrating plates 2 in row and column directions and allof the matrix electrodes 25 on the quartz crystal wafer 32 come into anelectrically conducted state.

Further, a layer of aluminum is formed at a total of the quartz crystalvibrating plate 2 from above the matrix electrode 25 by sputtering,vapor deposition or the like. Further, patterning is carried out byphotolithography and etching or the like, an electrode comprisingaluminum is formed at the vibrating arm 9 a, and the aluminum layer atan unnecessary portion of the inner side face 35 of the frame-likeportion 10, an outer edge portion of each quartz crystal vibrating plate2 or the like is removed. At this occasion, the electrode patterned atthe vibrating arm 9 a constitutes the inner electrode 24 and theelectrode patterned at the frame-like portion 10 constitutes the bondingelectrode 19. Further, the portion of the outer edge portion removingthe aluminum layer and exposing the matrix electrode 25 constitutes theabove-described recess portion 21.

Next, in vacuum, as shown by FIG. 4, the respective wafers areoverlapped to interpose the quartz crystal wafer 32 by the wafer 30 forthe lid portion and the wafer 31 for the base in the thicknessdirection. At this occasion, the lid side recess portion 11 and the baseside recess portion 14 are opposed to each other respectively, thereby,the cavity portion 15 is formed.

Under the state, the respective wafers are heated to a predeterminedtemperature. Along therewith, by an outside voltage applying apparatusor the like, a negative voltage is applied to the wafer 30 for the lidportion and the wafer 31 for the base, and positive voltage is appliedto the matrix electrode 25. At this occasion, since all of the matrixelectrodes 25 are electronically conducted on the quartz crystal wafer32, the voltage is applied to all of the matrix electrodes 25 byconstituting one point of an external electrode terminal brought intocontact with the matrix electrode 25. Further, the voltage is applied tothe bonding electrodes 19 by way of the matrix electrodes 25. As aresult, electrostatic attraction forces are produced between the bondingelectrode 19 and the one main face 30 a and between the bondingelectrode 19 and the one main face 31 a to strongly bring the bothmembers into close contact with each other to be bonded anodically.Thereby, the cavity portions 15 are sealed in airtight and thehermetically closed vessels 3 contiguous in row and column directionsare formed. Thereafter, the respective voltages are stopped, and thewafer 30 for the lid portion and the wafer 31 for the base are graduallycooled to return to room temperature. During a time period in whichtemperatures of the wafer 30 for the lid portion, the wafer 31 for thebase and the quartz crystal vibrating plate 2 or the like are elevatedand return to normal temperature, the wafer 30 for the lid portion, thewafer 31 for the base and the quartz crystal vibrating plate 2 arethermally expanded by elevating the temperatures, contracted by beingcooled gradually and returned to the original state. At this occasion,since thermal expansion coefficients of glass and quartz differ fromeach other, amounts of deforming the respective wafers differ from eachother and therefore, it is not preferable to elevate the temperaturesexcessively. Therefore, when the glass is soda lime glass, as thebonding electrode 19, aluminum capable of carrying out anodic bondingeven at a temperature equal to or lower than 300° C. is used.

Thereafter, the external terminals 20 are provided at the respectivehermetically closed vessels 3. That is, a thin film is formed bysputtering, vapor deposition or the like at other main face of the wafer31 for the base by providing a metal mask thereon. Thereby, a pair ofthe external terminals 20 extended from the inner face of the throughhole to the other main face of the wafer 31 for the base are provided.The external terminal 20 is connected to the bonding electrode 19 by wayof the through hole.

Further, the wafer 30 for the lid portion and the wafer 31 for the baseor the like are cut in a state of pasting a tape on the other main faceof the wafer 31 for the base. That is, the wafer 30 for the lid portionand the wafer 31 for the base and the like are installed at a dicing sawand are cut on straight lines connecting the through holes by a dicingblade in row and column directions. Thereby, the matrix electrode 25 isexposed from a side face of the hermetically closed vessel 3. At thisoccasion, the bonding electrode 19 is brought into a state of beingdisposed on an inner side of the recess portion 21.

Further, a total of the wafer 30 for the lid portion and the wafer 31for the base and the like is dipped into the solution of fluorocarbon ina state of being pasted to the tape. Thereafter, the wafer 30 for thelid portion and the wafer 31 for the base and the like are taken out,placed for a predetermined time period and thereafter heated. Then, theprotecting film 16 is formed at outer faces of the respectivehermetically closed vessels 3 and the recess portions 21. Further,although there is a case in which the solution invades a clearance ofthe tape when the respective wafers are dipped, since a surface of theexternal terminal 20 comprises Au and the solution comprisesfluorocarbon, the protecting film is prevented from being formed at theexternal terminal 20.

Thereafter, when the tape is exfoliated, singles of the quartz crystalvibrators 1 become the quartz crystal vibrators 1 shown in FIG. 1through FIG. 3.

Next, operation of the quartz crystal vibrator 1 according to theembodiment constituted in this way will be explained.

When a predetermined voltage is applied to the external terminal 20, thevoltage is applied to the quartz crystal vibrating piece 9 by way of thebonding electrode 19 and the inner electrode 24. Then, the vibratingarms 9 a carry out a flexural movement with a predetermined period indirections of being proximate to each other or remote from each other,that is, by a reverse phase mode by a piezoelectric effect.

Here, in the fluororesin layer or the like as the protecting film of therelated art, chipping, crack or the like is liable to be brought about.According to the embodiment, a defect, a crack or the like is preventedfrom being brought about as follows. There is provided the recessportion 21 recessed to the inner side of the hermetically closed vessel3 over the entire peripheries of the outer edge portion between the lidmember 6 and the quartz crystal vibrating plate 2 and between the basemember 7 and the quartz crystal vibrating plate 2, and the recessportion 21 is filled with the protecting film 16. Therefore, a dimensionof the protecting film 16 inside of the recess portion 21 extended tothe inner side of the hermetically closed vessel 3 becomes sufficientlylarge. Therefore, a strength of the protecting film 16 inside of therecess portion 21 against an external force is increased, for example,even when the quartz crystal vibrator 1 is pinched by tweezers or thelike, the protecting film 16 inside of the recess portion 21 isprevented from being chipped off. Further, crack or the like isdifficult to be brought about at the protecting film 16 inside of therecess portion 21, and even when crack is assumedly brought about, thecrack becomes difficult to reach the inner side end portion of theprotecting film 16 inside of the recess portion 21.

As described above, according to the quartz crystal vibrator 1 accordingto the embodiment, chipping, crack or the like can be prevented frombeing brought about at the protecting film 16 inside of the recessportion 21 and therefore, the bonding electrode 19 can be prevented frombeing corroded and soundness of the bonding electrode 19 can easily bemaintained over a long period of time. Further, since the bondingelectrode 19 is prevented from being corroded, leakage is not broughtabout, a change in the pressure of the cavity portion 15 formed insideof the hermetically closed vessel 3 is restrained and variations of theoscillation frequency and the resonance resistance value of the quartzcrystal vibrator 1 are maintained within rectified values for a longperiod of time.

Further, since the frame-like portion 10 is provided with the matrixelectrode 25 extended to the outer edge portion, when a plurality of thequartz crystal vibrating plates 2 are formed on the quartz crystal wafer32, all of the matrix electrodes 25 on the quartz crystal wafer 32 canelectrically be connected. Therefore, in anodic bonding, the voltage canbe applied to all of the bonding electrodes 19 on the quartz crystalwafer 32 by way of the matrix electrodes 25 by constituting the onepoint of the external electrode terminal brought into contact with thematrix electrode 25. Therefore, the plurality of quartz crystalvibrators 1 can efficiently and easily be fabricated. Further, since thematrix electrode 25 is provided with the corrosion resistance higherthan that of the bonding electrode 19, even when chipping or crack isbrought about at the protecting film 16 brought into contact with thematrix electrode 25, the matrix electrode 25 can be prevented from beingcorroded.

Further, although according to the embodiment, the recess portion 21 isprovided and a shape or the like of the recess portion 21 canpertinently be changed. For example, as shown by FIG. 6, an openingdiameter d of the recess portion 21 can be set to be larger than adiameter of an inner portion thereof. Thereby, the solution offluorocarbon can be facilitated to invade inside of the recess portion21, and the solution can swiftly be filled fully inside of the recessportion 21.

Embodiment 2

Next, a second embodiment of the invention will be explained.

FIG. 7 shows the second embodiment of the invention.

In FIG. 7, the same portions as constituent elements illustrated in FIG.1 through FIG. 6 are attached with the same notations and an explanationthereof will be omitted.

Basic constitutions of the embodiment and the first embodiment are thesame and an explanation will be given here of a point of difference.

According to the embodiment, the matrix electrode 25 is removed over anentire periphery of an inner edge portion of the frame-like portion 10,and the bonding electrode 19 is extended to the removed portion. Thatis, the bonding electrode 19 is extended in steps to the inner edgeportion of the frame-like portion 10 from each of the one main faces 6a, 7 a of the lid member 6 and the base member 7.

Here, when the matrix electrode layer remains at the inner side face 35of the frame-like portion 10 without being removed therefrom, thebonding electrode 19 on the side of the lid member 6 and the bondingelectrode 19 on the side of the base member 7 are short circuited.Hence, in forming the matrix electrode 25, a mask for exposure isprevented from being disposed at the inner edge portion of theframe-like portion 10. Further, the matrix electrode 25 is patterned byoverexposure. Therefore, the matrix electrode layer is removed from theinner side face 35 of the frame-like portion 10 over to the inner edgeportion. Further, the bonding electrode 19 is formed on the patternedmatrix electrode 25 as described above.

Thereby, the matrix electrode layer can be prevented from remaining atthe inner side face 35 and yield can be promoted.

Further, although the matrix electrodes 25 are provided over the entirefaces of the two faces of the frame-like portion 10, the invention isnot limited thereto but a portion, a dimension and a shape or the likeof the matrix electrode 25 at the frame-like portion 10 can pertinentlybe changed. That is, the matrix electrodes 25 may electrically beconnected to the bonding electrodes 19 and may electrically be connectedto at least portions of the matrix electrodes 25 contiguous to eachother in row and column directions on the quartz crystal wafer 32. Forexample, the matrix electrodes 25 may be formed linearly in row andcolumn directions.

Further, although the matrix electrode 25 is provided, the matrixelectrode 25 may be dispensed with. However, it is preferable to providethe matrix electrodes 25 when a plurality of the quartz crystal vibrator1 are summarizingly fabricated by using a wafer or the like as describedabove.

Further, although the protecting film 16 comprises optul DSX, theinvention is not limited thereto but the member can pertinently bechanged.

Further, also members of the bonding electrode 19 and the matrixelectrode 25 can pertinently be changed.

Further, although the plurality of quartz crystal vibrators 1 aresummarizingly fabricated by the wafer 30 for the lid portion and thewafer 31 for the base, the invention is not limited thereto but theplurality of quartz crystal vibrators 1 may individually be fabricated.

Embodiment 3

As a third embodiment of the present invention, an oscillator in whichthe above-mentioned piezoelectric vibrator is connected to an integratedcircuit as an oscillation piece is explained in conjunction with FIG. 8.

FIG. 8 is a rough schematic view showing the constitution of atuning-fork-type quartz crystal oscillator 38.

In FIG. 8, the tuning-fork-type quartz crystal vibrator 1 is set at agiven position on a board 40, while an integrated circuit for oscillatorindicated by numeral 43 is arranged close to the quartz crystalvibrator. Further, an electronic component 39 such as a capacitor isalso mounted on the board 40. These respective parts are electricallyconnected with each other through a wiring pattern not shown in thedrawing. The mechanical vibrations of a piezoelectric vibrator piece ofthe tuning-fork-type quartz crystal vibrator 1 are converted intoelectric signals due to the piezoelectric characteristic which thequartz crystal possesses and the electric signals are inputted to theintegrated circuit 43. In the inside of the integrated circuit 43, thesignal processing is performed and frequency signals are outputted andhence, the integrated circuit 43 functions as an oscillator. Theserespective constitutional parts are molded by resin not shown in thedrawing. By selecting, for example, a RTC (Real Time Clock) module orthe like as the integrated circuit 43, the integrated circuit 43 alsohas, besides a function of a single function oscillator for clock, afunction of controlling an operation day and time of the oscillator andan external apparatus and a function of providing information on timeand calendar to a user.

In the oscillator according to the invention, an effect similar to thatof the above-described piezoelectric vibrator can be achieved.Therefore, the oscillator can be functioned with stable accuracy over along period of time.

Embodiment 4

As a fourth embodiment of the present invention, an electronic apparatusused in a state that the above-mentioned piezoelectric vibrator isconnected to a time counting portion is explained in conjunction withFIG. 9. As an example of the electronic apparatus, a preferredembodiment on a portable information apparatus represented by a mobilephone is explained in detail.

First of all, as a premise, the portable information apparatus accordingto this embodiment is a development or an improvement of a wrist watchof the related art. The portable information apparatus resembles thewrist watch in appearance, arranges a liquid crystal display on aportion thereof which corresponds to a dial plate, and can display acurrent time and the like on a screen of the display. In using theportable information apparatus as a communication device, the portableinformation apparatus is removed from a wrist and a user can perform thecommunication in the same manner as a mobile phone of the related artusing a speaker or a microphone incorporated in the inside of a bandportion. However, the portable information apparatus is drasticallyminiaturized and is light-weighted compared to the conventional mobilephone.

Next, the functional constitution of the portable information apparatusaccording to this embodiment is explained in conjunction with thedrawing. FIG. 9 is a block diagram showing the constitution of theportable information apparatus 46 according to this embodimentfunctionally.

In FIG. 9, numeral 47 indicates a power source portion which supplieselectricity to respective functional parts described later. To be morespecific, the power source portion 47 is embodied by a lithium ionsecondary cell. To the power source portion 47, a control portion 48, atime counting portion 51, a communication portion 52, a voltagedetecting portion 53 and a display portion 56 are connected in parallelto each other, wherein the electricity is supplied to the respectivefunctional parts from the power source portion 47.

The control portion 48 controls the respective functional partsdescribed later and performs an operational control of the whole systemsuch as the transmission and reception of vocal data, the measurementand display of the current time and the like. The control portion 48, tobe more specific, is embodied by programs which are preliminarilywritten in a ROM, a CPU which reads out and executes the programs, a RAMwhich is used as a work area of the CPU and the like.

A time counting portion 51 is constituted of an integrated circuit whichincorporates an oscillation circuit, a register circuit, a countercircuit, an interface circuit and the like therein and thetuning-fork-type quartz crystal vibrator which is described in theembodiment 1 or 2. The mechanical vibrations of the tuning-fork-typequartz crystal vibrator are converted into electric signals due to thepiezoelectric characteristic which the quartz crystal possesses and theelectric signals are inputted to the oscillation circuit which isconstituted of a transistor and a capacitor. An output of theoscillation circuit is binarized and the binarized value is counted bythe register circuit and the counter circuit. The transmission andreception of signals are performed between the time counting portion 51and the control portion 48 through the interface circuit and the currenttime, the current date or the calendar information is displayed on thedisplay portion 56.

The communication portion 52 functions in the same manner as the mobilephone of the related art and is constituted of a wireless portion 57, avoice processing portion 58, an amplifying portion 62, a voiceinput/output portion 63, an incoming sound generating portion 67, aswitching portion 61, a call control memory portion 68 and a telephonenumber input portion 66.

The wireless portion 57 transmits and receives various kinds of datasuch as vocal data with a base station via an antenna. The voiceprocessing portion 58 codes and decodes the vocal signal inputted fromthe wireless portion 57 or the amplifying portion 62 described later.The amplifying portion 62 amplifies the signal inputted from the voiceprocessing portion 58 or the voice input/output portion 63 describedlater to a given level. The voice input/output portion 63 is, to be morespecific, a speaker or a microphone and amplifies an incoming call soundor a phone sound or collects a speaker's voice.

The incoming sound generating portion 67 generates an incoming callsound in response to calling from the base station. The switchingportion 61 changes over the connection between the amplifying portion 62and the voice processing portion 58 to the connection between theamplifying portion 62 and the incoming call generating portion 67 onlyat the time of receiving the incoming signal and hence, the generatedincoming call sound is outputted to the input/output portion 63 throughthe amplifying portion 62.

Here, the calling control memory 68 stores a program related to theoutgoing/incoming calling control of the communication. Further, thetelephone number input portion 66, to be more specific, is constitutedof number keys from 0 to 9 and some other keys and is served forinputting the telephone number of a telephone call destination or thelike.

The voltage detecting portion 53, when a voltage applied to therespective functional parts including the control portion 48 from thepower source portion 47 becomes lower than a given value, detects thelowering of the voltage and notifies the lowering of the voltage to thecontrol portion 48. The given voltage value is a value which ispreliminarily set as a minimum voltage for operating the communicationportion 52 in a stable manner and is a voltage of approximately 3V, forexample. The control portion 48, upon receiving the notification oflowering of the voltage from the voltage detecting portion 53, inhibitsthe operations of the wireless portion 57, the voice processing portion58, the switching portion 61 and the incoming sound generating portion67. Particularly, the stopping of the operation of the wireless portion57 which exhibits the large power consumption is indispensable.Simultaneously with such stopping of the operations, a message that thecommunication portion 52 is inoperable due to the shortage of theremaining battery amount is displayed on the display portion 56.

Due to the cooperative operation of the voltage detecting portion 53 andthe control portion 48, it is possible to inhibit the operation of thecommunication portion 52 and it is also possible to display theinhibition of the operation of the communication portion 52 on thedisplay portion 56.

In this embodiment, by providing a power source cutting portion 69 whichcan selectively interrupt the power supply of a portion corresponding tothe function of the communication portion, it is possible to stop thefunction of the communication portion in a more complete form.

Here, although the display of the message that the communication portion52 becomes inoperable may be performed using a letter message, thedisplay may be performed by more instinctive methods including a methodin which a mark “x” (meaning inoperable) is applied to a telephone iconon the display portion 56.

In the electric apparatus according to the invention, an effect similarto that of the above-described piezoelectric vibrator can be achieved.Therefore, the electric apparatus can be reliable and functioned withstable accuracy over a long period of time.

Embodiment 5

FIG. 10 is a schematic view showing a circuit block of a radio wavetimepiece 71 which constitutes an electronic apparatus according to afifth embodiment of the present invention. The embodiment shows a casein which the tuning-fork-type quartz crystal vibrator (piezoelectricvibrator) manufactured by the manufacturing method of the presentinvention is connected to a filter part of the radio wave timepiece 71.

The radio wave timepiece 71 is a clock which has a function of receivingthe standard electric wave containing time information and displayingthe time information by automatically correcting the time to an accuratetime. In Japan, transmission stations (transmitting facilities) whichtransmit the standard electric waves are located in Fukushima prefecture(40 KHz) and Saga prefecture (60 KHz) and these transmission stationstransmit the standard electric waves respectively. Long waves havingfrequency of 40 KHz or 60 KHz have a property that the long waves arepropagated on a surface of the earth and a property that the long wavesare propagated while being reflected between an ionosphere and thesurface of the earth and hence, the propagation range is broad wherebythe long waves cover the whole Japan with the above-mentioned twotransmission stations.

In FIG. 10, an antenna 74 receives the standard electric waves formed ofthe long waves of 40 KHz or 60 KHz. The standard electric waves formedof long waves are electric waves obtained by applying the timeinformation referred to as a time code to the carrier wave of 40 KHz or60 KHz using the AM modulation.

The received standard electric waves formed of long waves are amplifiedby an amplifier 75. Subsequently, the standard electric waves arefiltered by a filter part 80 containing quartz crystal vibrators 76, 79having the same resonance frequency as the carrier wave frequency andare synchronized with the carrier wave. The filtered signal of givenfrequency is detected and demodulated by a detecting/rectifying circuit81. Then, the time code is taken out through a waveform shaping circuit84 and is counted by a CPU 85. The CPU 85 reads out the information suchas the current year, the accumulated days, date, time and the like. Theread-out information is reflected on a RTC 86 and the accurate timeinformation is displayed.

Since the carrier wave is 40 KHz or 60 KHz, it is preferable to use theabove-mentioned vibrator having the tuning-fork-type structure as thequartz crystal vibrators 76, 79 which constitute the filter partsrespectively. Taking the long waves of 60 KHz, for example, as a sizeexample of the tuning-fork-type vibrator, it is possible to configurethe vibrating piece such that the vibrating piece has a total length ofapproximately 2.8 mm and a width size of a base portion thereof isapproximately 0.5 mm.

The piezoelectric vibrator which is manufactured by the manufacturingmethod of the present invention is connected to the filter part of theradio wave timepiece, thereby making it possible to further improve theendurance of the radio wave timepiece. Accordingly, it is possible toallow the radio wave timepiece to be operated over a long period whilemaintaining the highly accurate filter function of the radio wavetimepiece for a long period.

1. A quartz crystal vibrator comprising: a quartz crystal vibratingplate formed by surrounding a quartz crystal vibrating piece by aframe-like portion; an inner electrode provided at the quartz crystalvibrating piece for applying a voltage to the quartz crystal vibratingpiece; a hermetically closed vessel including a lid member and a basemember in a plate-like shape for interposing the quartz crystalvibrating plate in a thickness direction thereof; bonding electrodes forbonding provided between the lid member and the quartz crystal vibratingplate and between the base member and the quartz crystal vibrating plateand electrically connected to the inner electrode; and a protecting filmprovided at an outer face of the hermetically closed vessel forprotecting the bonding electrode; wherein recess portions recessed toinner sides of the hermetically closed vessel are provided at an outeredge portion between the lid member and the quartz crystal vibratingplate and between the base member and the quartz crystal vibratingplate, the protecting film is provided at the recess portion; andwherein the bonding electrode is disposed on the inner side of therecess portion.
 2. The quartz crystal vibrator according to claim 1,further comprising: an auxiliary electrode electrically connected to thebonding electrode and having a corrosion resistance higher than acorrosion resistance of the bonding electrode; wherein the auxiliaryelectrode is extended to the outer edge portion between the lid memberand the quartz crystal vibrating plate and the outer edge portionbetween the base member and the quartz crystal vibrating plate.
 3. Thequartz crystal vibrator according to claim 1, wherein an openingdiameter of the recess portion is set to be larger than a diameter of aninner portion of the recess portion.
 4. An oscillator, wherein thequartz crystal vibrator according to claim 1 is electrically connectedto an integrated circuit as an oscillation piece.
 5. An electronicapparatus including the quartz crystal vibrator according to claim 1.